MBB 142 lec Drosophila Flashcards
(121 cards)
1
Q
The best understood of all developmental model systems
A
Drosophila
2
Q
Drosophila hatches from the egg as a/an?
A
Larva
3
Q
Two axes which define early Drosophila body patterning
A
Antero-posterior and Dorso-ventral axes
4
Q
The four regions that the dorso-ventral axis of Drosophila is divided into (from ventral to dorsal)
A
Mesoderm, Neuroectoderm/ Ventral ectoderm, Dorsal ectoderm, Amnioserosa
5
Q
What is the amnioserosa?
A
An extraembryonic membrane that is sloughed off during development
6
Q
The region/s that the ventral ectoderm will develop into
A
Ventral epidermis and Neural tissue
7
Q
The region/s that the dorsal ectoderm will develop into
A
Epithelium
8
Q
The regions that the antero-posterior axis will develop into (3)
A
Head, Thorax, and Abdomen
9
Q
Number of parasegments
A
14
10
Q
Number of thoracic and abdominal segments
A
3 and 8
11
Q
Distinguishing characteristics of the segments (2)
A
Denticles and Bristles
12
Q
Specialized structure at the posterior end of the larva
A
Telson
13
Q
Specialized structure at the anterior end of the larva
A
Acron
14
Q
Process of change from larva to adult
A
Metamorphosis
15
Q
Group of cells set aside in the embryo that eventually give rise to adult structures, such as the wings and legs
A
Imaginal discs
16
Q
Does the antero-posterior axis finish developing first before development of the dorso-ventral axis begins?
A
No, they occur simultaneously
17
Q
The early multinucleate stage in Drosophila development
A
Syncytial blastoderm
18
Q
What is the third dimension in the development of Drosophila, and when does this dimension form?
A
The proximal-distal axis, which forms during gastrulation
19
Q
These genes set up the body axes
A
Maternal genes
20
Q
Those genes which are required for subsequent development of Drosophila at later developmental stages
A
Zygotic genes
21
Q
The four main classes of zygotic genes
A
Gap genes, Pair-rule genes, Segment polarity genes, and Homeotic/Selector genes
22
Q
Selector genes depend on which sets of zygotic genes?
A
Gap genes, and Pair-rule genes
23
Q
Three classes of maternal genes that define the antero-posterior axis
A
Those that affect anterior regions, posterior regions, and the terminal regions
24
Q
T/F: Maternal genes establish differences in the antero-posterior axis after fertilization
A
F
25
Mutations that, when present in the mother, do not affect her but affects her progeny
Maternal-effect mutations
26
T/F: Bicoid gene expression affect nanos gene expression
F, they work independently
27
Mutations in what maternal gene will lead to the absence of the acron and telson?
Torso
28
From what germ layer does the ovary of the mother derive from?
Mesoderm
29
Where in the unfertilized egg is bicoid mRNA localized?
Anterior end
30
When is bicoid mRNA translated?
At fertilization
31
If a normal fertilized egg has parts A, B, C, D, and E (from anterior to posterior), and a mutant bicoid fertilized egg was injected with external bicoid at site C. What will be the arrangement of parts in the injected bicoid mutant? Assume that a larva can only have 5 parts in its antero-posterior axis.
C, B, A, B, C
32
What is the maternal gene that encodes for a protein that relocates bicoid mRNA to the anterior end of an egg?
Exuperantia
33
What is the half-life of the bicoid protein?
30 minutes
34
T/F: For proper patterning of the antero-posterior axis, a functioning bicoid gradient is enough.
F, both ends must be specified
35
This group of maternal genes control the posterior development of the Drosophila body plan
Posterior group genes
36
The development of what structure is impeded by mutations in posterior group genes?
Abdomen
37
This maternal gene product localizes nanos mRNA to the posterior end of the fertilized egg
Oskar
38
This maternal gene product specifies the posterior germ plasm, which eventually gives rise to the germ cells of Drosophila
Oskar
39
Nanos is present in the unfertilized egg as what?
mRNA
40
What maternal gene product/s makes a morphogen gradient with its highest level at the posterior end?
Nanos and Caudal
41
The expression of what (specify source) is inhibited by nanos protein?
Maternal hunchback
42
What causes the translation of zygotic hunchback?
Bicoid
43
Nanos prevents the expression of maternal hunchback by binding to the complex of? (2)
Maternal hunchback mRNA and Pumilio
44
If a maternal hunchback mutant were to be created, but somehow nanos expression was disturbed in the process, will the egg develop to be normal still? Why?
Yes, because the only function of nanos is to suppress maternal hunchback expression
45
Where is caudal mRNA initially found?
Uniformly distributed in the egg
46
What inhibits caudal protein expression?
Bicoid
47
Does the development of the two terminal regions utilize separate pathways?
No, both use the same pathway
48
What is the receptor protein that is important in specifying the terminal regions of the egg?
Torso
49
What is the ligand of the torso protein?
Trunk
50
Before fertilization, where (specify region) is the ligand of torso bound to?
The terminal portions of the side of the vitelline envelope facing the egg
51
What do you call the space in between the vitelline envelope and the cell membrane?
Perivitelline space
52
What prevents the ligand of torso from dispersing to the non-terminal regions of the egg?
The low amount of the ligand and the fact that most of it gets bound by torso at the terminal leads to a lack of dispersal.
53
What is the receptor type of the torso protein?
Receptor tyrosine kinase
54
What secretes the spatzle protein into the vitelline space?
Follicle cells
55
Where is pipe mRNA transcribed in the vitelline space by follicle cells?
Ventral 1/3 of the egg
56
What other maternal genes, aside from pipe, are important in the processing of spatzle? (3)
Easter, Nudel, and Windbeutel
57
What receptor accepts a particular form of spatzle as its ligand?
Toll
58
What is the form of spatzle accepted by its ligand?
Fragmented form
59
In what regions of the egg is Toll located in the plasma membrane?
Everywhere
60
What is the original location of the dorsal protein?
At the cytosolic periphery of the egg
61
T/F: The dorsal protein acts as both a morphogen and a transcription factor.
T
62
The term used to describe embryos in which no ventral structures develop.
Dorsalized
63
What prevents the dorsal protein from prematurely entering the nuclei?
Cactus
64
What are the human homologs of dorsal and cactus proteins?
NF-kB, and I-kB
65
Give the two maternal gene products that help in the transduction of the signal by Toll to allow the entry of dorsal protein inside the nuclei of the syncytial blastoderm.
Tube and Pelle
66
What is the effect of the signal from the activated Toll protein that allows for nuclear dorsal protein entry?
Degradation of bound cactus protein
67
What is the structure in which the original stem cell (that gives rise to the oocyte and nurse cells) is contained?
Germarium
68
What do you call the outgrowths of the germarium containing the developing oocyte?
Egg chamber
69
How many times does the original stem cell divide to give rise to the oocyte as well as its nurse cells?
4 times
70
What allows the nurse cells to provide to the oocyte the various maternal mRNAs that it needs for development?
Cytoplasmic bridges
71
What cells are mainly responsible for the patterning of the developing oocyte?
Follicle cells
72
What secretes the vitelline envelope, as well as the chorion of the Drosophila egg?
Follicle cells
73
First visible sign of antero-posterior axis development in the egg
Movement of egg towards one end of the egg chamber
74
What facilitates the attachment of the oocyte to the follicle cells?
E-cadherin
75
What facilitates the inductive signal produced by the oocyte to the follicle cells it contacts?
Gurken
76
What family does the gurken protein belong to?
TGF-alpha family of proteins
77
The receptor for the gurken protein is located where?
On the follicle cells contacting the oocyte
78
What is the receptor for the gurken protein?
Torpedo
79
What is the kind of receptor for the gurken protein receptor?
Receptor tyrosine kinase
80
What is the response of the egg upon receiving the signal from the follicle cells due to activation of torpedo?
Reorganization of microtubules on the antero-posterior axis
81
Where is bicoid mRNA produced?
By the nurse cells on the anterior portion of the egg
82
Which occurs first, the organization of the antero-posterior axis or the dorso-ventral axis, at least in the developing oocyte?
Antero-posterior axis is first
83
How many times is gurken protein expression activated during the determination of the axes of the developing oocyte?
Two times, one during antero-posterior axis determination, and another time during dorso-ventral axis determination
84
Most of the zygotic genes encode what type of proteins?
Transcription factors
85
What are the different regions present in the dorso-ventral axis, and what genes are expressed in each?
Mesoderm - Twist and Snail
Between the mesoderm and the neuroectoderm - Single-minded)
Ventral ectoderm/ Neuroectoderm - Rhomboid
Dorsal ectoderm - Tolloid and Decapentaplegic
Amnioserosa - Zerknullt
86
The expression of what genes is activated by high amounts of dorsal protein?
Twist and Snail
87
What activates rhomboid gene expression? What represses it?
Low amounts of dorsal protein; Snail
88
Are there regions in the fertilized egg in which both twist and decapentaplegic expression is absent? Where would this region most likely be?
Yes. It would most likely be at the neuroectoderm.
89
What determines the ventral pattern of early embryo?
Decapentaplegic
90
What is the homolog of decapentaplegic?
BMP-4
91
When does the embryo become cellular? (in terms of the development of the dorso-ventral axis)
After the establishment of the dorsal protein gradient/ After twist and snail expression
92
Why is sog necessary in the determination of the dorso-ventral axis?
It is because decapentaplegic (dpp) is an autoregulator, meaning that is activates its own expression. Sog helps prevent the spread of dpp to the ventral regions by preventing its autoregulatory effect.
93
What are the first genes to be expressed in the antero-posterior axis?
Gap genes
94
T/F: Some gap genes do not code for transcription factors, and merely code for proteins that function in the stabilization of parasegmentation.
F, all gap genes code for transcription factors.
95
Name five examples of gap genes.
Hunchback, Knirps, Giant, Kruppel, and Tailless
96
T/F: The phenotype of gap gene mutants only involves the lack of certain parts of the mutant embryo.
F, gap genes are known to have effects other than the determination of the antero-posterior axis.
97
T/F: The multiple regions of giant expression is indicative of an aperiodic pattern of transcription.
T
98
Is the embryo a syncytial or cellular blastoderm at the time of gap gene expression?
The embryo is still a syncytial blastoderm.
99
The expression of gap genes is controlled by...
Bicoid, hunchback, as well as the expression of other gap genes
100
Bicoid is a member of what family of transcriptional activators?
Homeodomain family
101
The transposon used to artificially introduce genes in Drosophila
P-element
102
The enzyme responsible for the hopping of P-elements from one region of the Drosophila chromosome to another
Transposase
103
An exogenous protein that can be used to temporally and spatially control the expression of the inserted genes in Drosophila.
GAL4
104
A technique in which a gene is randomly inserted into regions in the chromosome, and leads to the temporal and spatial expression of the inserted gene depending on the promoter and enhancer regions found near the insert site.
Enhancer trap
105
Describe the dependence of Kruppel expression on the levels of hunchback protein.
Kruppel expression is inhibited by both high and low levels of hunchback expression.
106
Describe the dependence of knirps expression on the levels of hunchback and tailless.
Knirps expression is inhibited both by high levels of hunchback, as well as the presence of tailless
107
This is the modules from which segments derive.
Parasegments
108
The segments that will fuse to form the head.
C1, C2, and C3.
109
First visible signs of segmentation in the embryo.
The formation of transient grooves.
110
Each segment is made out of? (in terms of parasegments)
The anterior portion of one parasegment, and the posterior portion of the next
111
The parasegments are delimited by the action of what genes?
Pair-rule genes
112
T/F: Pair-rule gene expression, as well as gap gene expression, are both periodic in that multiple regions of expression are found in each.
F, pair-rule gene expression is periodic, while that of gap genes is aperiodic
113
Does the expression of pair-rule genes depend on the wave-like expression of a corresponding morphogen?
No, pair-rule gene expression depends on the combination of particular transcription factors, such as bicoid, hunchback, as well as the gap genes.
114
The boundaries of the second even-skipped gene is determined by...
The levels of Kruppel and giant expression
115
Give three examples of pair-rule genes.
Even-skipped, Hairy, and Fushi tarazu
116
The expression of fushi tarazu depends on...
Expression of primary pair-rule genes, such as even-skipped and hairy
117
The formation of the third parasegment depends on activation of even-skipped by...
Expression of bicoid and hunchback above a certain threshold level
118
T/F: Segment polarity genes encode for transcription factors only.
F, they encode for a diverse kind of proteins.
119
The segment polarity genes act in a syncytial or cellular environment?
Cellular
120
The expression of this gene allows for setting up cell lineage boundaries
Engrailed
121
What do you call a gene which confers an identity to specific regions, and so is required to be activated for extended periods of time?
Selector genes
